In electrical power systems, such as automotive power systems, it is often desirable to provide a user with facility for connecting a load alternately to first and second connection points at which electrical power is available, either from the same or separate power sources. For example, in an automotive electrical power system, a user may desire to connect an electrical load, such as the cigar/cigarette lighter socket, to the vehicle battery power system directly rather than through the ignition switch. In this way, in this specific example, the cigar/cigarette outlet socket of the vehicle may be employed for supplying electrical power to accessories, such as audio accessories or an emergency lamp, independent of the vehicle ignition switch.
A general object of the present invention is to provide a circuit arrangement by means of which a user may selectively and alternately connect an electrical load to either of two electrical power connection points. A further object of the present invention is to provide a circuit arrangement of the described character that is constructed in such a way as to ensure that the load cannot be connected to both power connection points simultaneously. Another and more specific object of the present invention is to provide a circuit arrangement of the described character that is economical to manufacture, that employs standard electrical components, and that may be readily and easily employed in the field by an untrained user for connecting the electrical load back and forth between the two power sources. As applied specifically to an automotive electrical power system, it is a further object of the present invention to provide a circuit arrangement of the described character for connecting a vehicle electrical load to the vehicle battery power system either directly so that the load is powered continuously, or through an ignition switch so that the load is powered only when the ignition switch is turned on.
A circuit arrangement for connecting an electrical load alternately to first and second points at which electrical power is available in accordance with the present invention includes a plurality of electrical contacts with a first contact being for connection to the first power connection point, a second contact being for connection to the second power connection point and a third contact for connection to the load. A fused connector is connectable to the contacts in a first position between the first and third contacts to connect the load to the first power connection point, and alternatively in a second position between the second and third contacts to connect the load to the second power connection point. The pluralities of electrical contacts in the preferred embodiments of the invention are arranged such that fused connectors cannot be connected in both of the first and second positions simultaneously, so that the load cannot be connected to both power connection point simultaneously.
In the preferred embodiments of the invention, the fused connector takes the form of an automotive-type fuse assembly having parallel coplanar male spade-type contact plugs. The plurality of contacts comprise female spade-type contact receptacles disposed relative to each other for removable reception of the male spade-type contact plugs of the fused connector in either of the first and second positions.
As applied specifically to an automotive electrical power system, a circuit arrangement in accordance with the present invention includes a plurality of at least three female spade-type contact receptacles, of which a first is for connection directly to the vehicle battery power system, a second is for connection to the vehicle ignition switch and the third is for connection to the load. The spade-type contact receptacles are disposed relative to each other for receiving an automotive-type fuse assembly having parallel coplanar male spade-type contact plugs alternately in a first position between the first and third contact receptacles and a second position between the second and third contact receptacles. In a first embodiment of the invention, the contact receptacles comprise three contact receptacles disposed in lateral alignment with each other, with the outer receptacles being connected to the vehicle/battery power system and the ignition switch, and the middle contact being connected to the load. In a second embodiment of the invention, the plurality of contact receptacles comprise four contact receptacles disposed in aligned coplanar pairs at right angles to each other. One contact receptacle of each pair is connected to the load and the other contact receptacle of each pair is connected to the vehicle battery power system either directly or through the ignition switch.